Ping:
https://gcc.gnu.org/ml/gcc-patches/2017-05/msg01428.html
On 05/17/2017 06:04 PM, Martin Sebor wrote:
While working on a new warning for unsafe conversion I noticed
that the existing warnings that diagnose these kinds of problems
are missing some useful detail. For example, given declarations
of an integer Type and an integer Constant defined in some header,
a C programmer who writes this declaration:
Type x = Constant;
might see the following:
warning: overflow in implicit constant conversion [-Woverflow]
To help the programmer better understand the problem and its impact
it would be helpful to mention the types of the operands, and if
available, also the values of the expressions. For instance, like
so:
warning: overflow in conversion from ‘int’ to ‘T {aka signed char}’
changes value from ‘123456789’ to ‘21’ [-Woverflow]
The attached simple patch does just that. In making the changes
I tried to make the text of all the warnings follow the same
consistent wording pattern without losing any essential information
(e.g., I dropped "implicit" or "constant" because the implicit part
is evident from the code (no cast) and explicit conversions aren't
diagnosed, and because constant is apparent from the rest of the
diagnostic that includes its value.
Besides adding more detail and tweaking the wording the patch
makes no functional changes (i.e., doesn't add new or remove
existing warnings).
Martin
PS While adjusting the tests (a painstaking process) it occurred
to me that these kinds of changes would be a whole lot easier if
dg-warning directives simply checked for "-Woption-name" rather
than some (often arbitrary) part of the warning text. It might
even be more accurate if the pattern happens to match the text
of two or more warnings controlled by different options.
It's of course important to also exercise the full text of
the warnings, especially where additional detail is included
(like in this patch), but that can be done in a small subset
of tests. All the others that just verify the presence of
a warning controlled by a given option could use the simpler
approach.
